I'll have to check a bit later for that, although isn't INCOMING_RESURRECT_CHANGED only for when the cast of a spell begins? When mass rez goes off it's just an aoe from the caster on anyone in range.

Yes, but ideally, this will happen:

1. Player A starts casting Mass Res.
2. IRC fires for Player B, who is dead, because a resurrection is casting that will affect them.
3. Player C dies.
4. IRC fires for Player C, who is now dead, because a resurrection is casting that will affect them.
5. Player B finishes casting Mass Res.
6. IRC fires for both Player B and Player C, because a resurrection relevant to them is no longer casting.

If INCOMING_RESURRECT_CHANGED doesn't fire this way, it will mean I need to add a bunch of extra code to keep track of dead units myself.